USAT makes a "Prestige Series" of locomotives that are die cast metal rather than plastic.

The GG-1 is one of these, a very fine model in scale and with a lot of working goodies, including sound and powered pantographs.

USAT states that it requires a minimum 8 foot diameter, but 10 foot diameter would be better.

The electronics, are, as usual for the Presteige series, unique and complex. The basic system is a QSI decoder, of an older vintage.

Thus it will run on DC or DCC and will also respond to the Quantum Engineer "programming" where a series of quick DC polarity reversals can control functions.

Out of the box, it seems that the maximum speed of the loco is slow, but you can change DCC CV 5 to 255 (max speed) and that cleared it up for a friend of mine.

One thing to remember if you buy one, the front pilots are very close to the rails, and unless you have perfect trackwork, you WILL ground them at some time to the rails, and you WILL destroy some of the electronics.

Unless you have perfect trackwork, you should grind some of the pilot off on the underside and I would recommend gluing a thin piece of styrene to boot.

Been there, done that, and the electronics are expensive and can be hard to come by.